This invention relates to vibratory tuning of rotating blades and more particularly to tuning such blades to reduce vibration of their trailing edges.
As turbine blades rotate, they are subjected to intermittent forces as they pass the stationary blades thus providing continual excitation, which results in high frequency vibration. The trailing edges of the blades, which are relatively thin, are particularly susceptible to such vibration which in one mode or form is termed panel modes and includes an infinite series of vibrations within this mode.
It is difficult to avoid resident excitation when the blades are long as the natural frequencies span a considerable range and there are a multiplicity of disturbances to excite vibration. By controlling the natural frequency in the panel mode resonant excitation of the trailing edges of the blades can be avoided by selecting numbers of stationary blades which will not result in natural frequency excitation.